GA Migration Python PostCommit Sharding Dataframe IO

[MarcoRob]

As part of the migration of Precommit and Postcommit Jobs from Jenkins to GA in self-hosted runners, this PR contains:

• Migrated workflow job-postcommit-python-dataframe-io.yml

The migrated workflow was added to CI.md

DO NOT MERGE until the effort to use self-hosted runners is completed #22703

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[damccorm]

LGTM (outside of the tiny nit), thanks!

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[damccorm]

LGTM, thanks

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[github-actions]

This pull request has been marked as stale due to 60 days of inactivity. It will be closed in 1 week if no further activity occurs. If you think that’s incorrect or this pull request requires a review, please simply write any comment. If closed, you can revive the PR at any time and @mention a reviewer or discuss it on the dev@beam.apache.org list. Thank you for your contributions.